RFR: 8212827: GlobalCounter should support nested critical sections

[Robbin Ehn]

Hi Kim,

Looks good, thanks!

/Robbin

On 26/10/2018 22:16, Kim Barrett wrote:
>> On Oct 26, 2018, at 4:06 AM, Robbin Ehn <robbin.ehn at oracle.com> wrote:
>> I would like the return value here:
>> inline uintx GlobalCounter::critical_section_begin(Thread *thread) {
>> And thus the parameter here:
>> 46 inline void GlobalCounter::critical_section_end(Thread *thread, uintx begin_value) {
>> be an opaque type so we don't leak out the implementation, but as long as the
>> GlobalCounter have the implementation as name, that doesn't help much.
>>
>> I'm thinking of something like:
>> inline RCUContext RCU::critical_section_begin(Thread *thread) {
>> inline void RCU::critical_section_end(Thread *thread, RCUContext context) {
>> Or
>> inline CSContext CriticalSection::begin(Thread *thread) {
>> inline void CriticalSection::end(Thread *thread, CSContext context) {
> 
> Giving this value it's own type name seems like a good idea.  I didn't
> want to go so far as an actual class wrapper though, so just added a
> typedef for CSContext, even though that's weak.  Better would be a
> C++11 enum class, e.g.
>    enum class CSContext : uintx {};
> I've written the code as if it was that (e.g. using static_casts for
> conversions where needed).  I'll file an RFE to change the type,
> blocked by the C++11/14 JEP.
> 
> Making that change required adding an #include of globalCounter.hpp to
> concurrentHashTable.hpp. While there, I added a couple more obviously
> missing #includes to that file.  I didn't verify that what I added was
> sufficient to #include this file without other preceeding #includes.
> 
> There were enough changes involved in this that I'm providing new
> webrevs for your consideration:
> full: http://cr.openjdk.java.net/~kbarrett/8212827/open.01/
> incr: http://cr.openjdk.java.net/~kbarrett/8212827/open.01.inc/
> 
> Testing: local (linux-x64) tier1.
>